Baltimore police aren't just looking to arrest criminals anymore, they're trying to get inside their heads.

Officers are distributing cards designed to intimidate suspects arrested in East Baltimore, and the department is developing a video to counter a recent DVD in which potential witnesses are threatened. The Baltimore Police Department is even thinking about placing officers atop lifeguard chairs in the most violent parts of the city.

"It's psychological warfare," said Police Commissioner Leonard D. Hamm. "It's part of the crime plan to target violent people."

Much of the campaign is modeled after military tactics to demoralize and influence an enemy, and many say it demonstrates a local shift toward a style of policing that promotes direct dialogue among police, criminals and embattled communities. It also adds a new dimension to Baltimore's long-running struggle to reduce shootings and killings.

The city recorded 278 homicides last year, more than any other city of similar size.

"We don't think we can win over hard-core criminals with a 3-by-5 card or a DVD," said police spokesman Matt Jablow, "but we can make a difference with the people who are teetering."

Police have identified the three areas with the most homicides and shootings - in Northwest Baltimore, East Baltimore and West Baltimore. Police are swarming to those sections. At times, those parts of the city are flooded by 10 to 15 officers where perhaps one patrolled previously.

The new police commissioner also is pushing intelligence-driven policing that targets specific people in addition to areas.

In many ways, the new philosophy mirrors recent efforts in Boston, said Jean McGloin, a University of Maryland criminologist. Starting in the mid-1990s, police, clergy and other leaders there called regular meetings of suspected gang members. They told the men to start receiving assistance from social services and give up crime, or they would be hounded by police.

Such actions build on a widely held philosophy in policing: People make deliberate decisions to commit crimes, and those decisions can be influenced by altering their environment, McGloin said.

An example of such influence is heightening the perceived risk of committing crimes. Police do that by installing surveillance cameras, increasing street lighting or pushing a message that more police are on the streets, she said.

Stern warning

So as the 173 detectives of the department's organized crime division hit the streets in East Baltimore, they do so armed with cards that carry a stern message conceived by Chief Anthony Barksdale.

One side states: "By any legal means necessary."

The other reads, "You were arrested today in a community that will no longer tolerate the violence that has plagued it for generations. More officers are on patrol in this key area than ever before. The Baltimore Police Department will not reduce its enforcement until the violence stops. Spread the word."

On a recent night, officers searching a home in the 2400 block of E. Madison St. handcuffed three middle-aged women as police scoured the rowhouse for cocaine.

The women sat on the couch, their hands behind their back and the cards resting atop their thighs. One said she couldn't read it.

"When you put your glasses on, you're going to have to read that card," said Deputy Maj. Dean Palmere. "It tells you what's going on in your community." For example, he said, people breaking the law have a greater chance of being arrested because of increased enforcement.

The program reminds Allison B. Gilmore - the author of a book about psychological warfare - of the United States' and Gen. Douglas MacArthur's efforts to win over the Philippines during World War II.